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The purpose of this paper is to provide a systematic method to perform long‐term reliability assessment of gold (Au) and copper (Cu) ball bonds in fineline ball grid array package. Also with the aim to study the apparent activation energies (E_aa) and its associated wearout mechanisms of both Au and Cu wire in semiconductor device packaging. This paper discusses the influence of wire type on the long‐term reliability and mechanical performance after several component reliability stress tests.

A fineline ball grid array (FBGA) package with Cu and Au wire bonds was assembled with green molding compound and substrate. Samples are subjected for long‐term high temperature storage bake test at elevated temperatures of 150°C, 175°C and 200°C. Long‐term reliability plots (lognormal plots) are established and E_aa of both ball bonds are determined from Arrhenius plots. Detailed failure analysis has been conducted on failed sample and HTSL failure mechanisms have been proposed.

Reliability results show Au ball bond in FBGA package is observed with higher hour‐to‐failure compared to Cu ball bonds. The E_aa value of high temperature storage life (HTSL) reliability for Au ball bond is lower than Cu ball bond. Typical HTSL failure mechanism of Au ball bond is induced by micro‐voiding and AuAl intermetallic compound (IMC) micro‐cracks while CuAl IMC micro‐cracking (induced by Cl⁻ corrosion attack and micro‐cracking) caused wearout opens in Cu ball bond. These test results affirm the test‐to‐failure data collected is a useful method for lifetime prediction and E_aa calculation.

The paper reveals higher reliability performance of Cu ball bond in FBGA flash memory package which can be deployed in flash memory FBGA packaging with optimised package bill of materials.

The test‐to‐failure methodology is a useful technique for wearout reliability prediction and E_aa calculation.

The purpose of this paper is to discuss how experimentation with open Internet of Things data can be institutionalised in an inclusive manner at scale.

The approach is conceptual, addressing key challenges discussed in the literature on experimental cities. This exposition of the problem of scaling experimentation is anchored in findings from two projects (Dampbusters and OrganiCity), which seek to implement experimentation as a practice of sustainable digital urban development.

One central finding is that local interventions need transferable frameworks and mechanisms to achieve scaling effects of experimentation as a practice. In addition, experimentation must embed common engagement principles, structures of data and interfaces, and governance principles across use cases to be scaled.

The authors outline how and why experimentation can be a useful approach to address challenges of implementing urban informatics into concrete uses and procedures for co-creation. Based on reports from two projects, the authors develop recommendations for experimentation at scale that reflect the need for engagement principles, the need for common data structures and interfaces, as well as governance principles.